Rock cutting apparatus

ABSTRACT

A rock cutting assembly of the type mounted to a machine capable of exerting downward force includes a plurality of cutters. Each cutter is connected with one of a plurality of separate cylinders for distributing the downward force provided by the machine evenly to each of the cutters.

TECHNICAL FIELD

[0001] This invention relates generally to an improved rock cuttingassembly for use with a heavy machine capable of providing downwardforce upon the assembly for breaking and cutting rock.

BACKGROUND ART

[0002] A rock cutting assembly is typically mounted to a machine capableof exerting downward force upon the assembly. The assembly includes acutter wheel to which the downward force is focused. The cutter wheelbreaks hard surfaces it contacts from the pressure exerted by the wheelagainst the hard surface. These surfaces include rocks, concrete,asphalt and any other surface desired to be penetrated. Rock cutters ofthis type are used to cut trenches in rocky terrain as well as to shavelayers off of concrete roadways.

[0003] Much of the rock cutter apparatus of the prior art includes onlya single cutter wheel capable of cutting only a narrow trench.Occasionally, however, the use of more than one cutter wheel isdisclosed. One such example is U.S. Pat. No. 4,175,886 to Moench et al.,which discloses an apparatus for cutting asphalt. While the Moench etal. patent is useful for cutting a wide trench into a smooth surface,such as an asphalt roadway, its practicality is limited. Because each ofthe cutter wheels rotate upon the same shaft, uneven forces will beexerted upon the wheels when cutting a path into a disparate surface.These uneven surfaces can produce forces which induce premature failureof the rock cutting apparatus. In addition, the cutter wheels can besubjected to side forces induced when the mobile machine to which theapparatus is mounted turns. Side forces can cause the premature failureof bearings that support the cutter wheels. A failed bearing immobilizesa cutter wheel requiring the removal of the apparatus from service forrepair.

[0004] Accordingly, a need exists for a cutter apparatus capable ofcutting a wide trench into a disparate surface as well as into a smoothsurface. Further, a need exists for a rock cutter apparatus that willevenly distribute the forces generated while cutting rock for preventingdamage to the apparatus. The present invention is directed to overcomeone or more of the problems as set forth above.

DISCLOSURE OF THE INVENTION

[0005] In one aspect of this invention, a rock cutting assembly mountedto a machine capable of exerting downward force includes a plurality ofcutters. Each cutter is coupled to a cylinder which generates a downwardforce upon the cutter. By affixing the cutters to a plurality ofcylinders, the forces applied by each cutter are more evenly distributedwhen cutting a disparate surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a perspective view of the subject invention mounted to aheavy duty machine.

[0007]FIG. 2 is a top perspective view of the subject invention showingthe cylinder pins.

[0008]FIG. 3 is a side view of the subject invention.

[0009]FIG. 4 is a sectional view of the subject invention along lineIV-IV of FIG. 3.

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] Referring to FIG. 1, a rock cutting assembly is shown generallyat 10 mounted to a machine 12 capable of exerting downward force uponthe assembly 10. The assembly 10 includes a plurality of cutters 14 forcutting rock, concrete, or other hard surfaces. In the preferredembodiment, the assembly 10 includes at least two cutters 14, but caninclude four, six, or more. FIG. 1 shows an assembly 10 having fourcutters 14. Typically, the number of cutters 14 used is inverselyproportional to the hardness of the cutting surface. For example, aconcrete surface with 3,000 psi compressive strength may optimally allowsix or more cutters 14 for breaking the surface. However, a natural rockwith up to 30,000 psi compressive strength may permit a maximum of twocutters 14. It is understood by those of skill in the art of rockbreaking that pressure on a rock from a cutter 14 increases as surfacearea of contact between the cutter(s) 14 and the rock decreases.Therefore, an assembly 10 having only two cutters 14 will producegreater pressure upon a rock than an assembly 10 having four cutters 14of similar size.

[0011] The assembly 10 includes a plurality of cylinders 16. Each of thecylinders 16 supports at least one of the cutters 14. In the preferredembodiment, the cylinders 16 take the form of a hydraulic strut forapplying downward force upon the cutters 14. The cylinders 16 evenlydistribute the downward force generated by the machine 12, providingoperational benefits that will be discussed further hereinbelow.

[0012] As best shown in FIG. 2, an assembly frame 18 includes aplurality of cylinder pins 20 affixed thereto for pivotally supportingthe cylinders 16. Each of the cylinder pins 20 pivotally support one ofthe cylinders 16 for allowing the cylinder 16 to pivot in asubstantially vertical plane.

[0013] The assembly frame 18 is preferably pivotally affixed to a caster22 for allowing the assembly frame 18 to pivot in a substantiallyhorizontal plane. The caster 22 reduces side forces on the cutters 14specifically, and on the assembly 10 generally, when the machine 12turns by allowing the assembly 10 to pivot. Thus, the utility life ofthe cutters 14 is extended by the introduction of the caster 22 to theassembly 10.

[0014] Each of the cutters 14 includes a cutter wheel 24. In thepreferred embodiment, the cutter wheel 24 comprises hardened steel.However, as required, cutter wheels 24 having carbide inserts or otherdurability mechanisms may be used. The cutter wheel 24 rotates upon abearing (not shown) as is commonly practiced in the art of stonebreaking. Frequently, the bearings fail when subjected to high sideforces Thus, the caster 22, by reducing the side forces on the cutterwheel 24 increases the life of the bearing.

[0015] Each of the cutters 14 includes a cutter frame 26 supporting thecutter wheel 24. The cutter frame 26 comprises a horizontal bar 28having a pair of brackets 30 extending down therefrom. The cutter wheel24, disposed on a bearing between the brackets 30, is driven to rotateby friction forces from the rock surface as the assembly 10 is advanced.Through rotation, erosion of the cutter wheel 24 and the stress upon theassembly 10 from friction forces are significantly reduced.

[0016] A plurality of support arm pairs 32 supports each cutter frames26, as illustrated in FIG. 4. Each of the support arm pairs 32 has oneor more cutter frames 26 fixedly attached therebetween. Each of thesupport arm pairs 32 is pivotally attached to the assembly frame 18 andat an opposite end a cutter frame 26. As best shown in FIG. 3, thepivotal attachment of the support arms to the assembly frame 18 allowseach cutter 14 to move in a vertical direction independent of theassembly frame 18, the other cutters and of the machine 12 while stillproviding latitudinal support to the cutter 14.

[0017] The support arm pairs 32 are arranged having each succeedingsupport arm pair disposed between each preceding support arm pair. Asbest represented in FIG. 4, the distance between the support armsdecreases for each succeeding support arm pair. For an assembly 10having at least a first support arm pair 34, and a second support armpair 36, the first pair 34 is disposed between the second pair 36. Foran assembly 10 having a third pair 38 and a fourth pair 40 of supportarms, the second pair 36 is disposed between the third pair 38, and thethird pair 38 is disposed between the fourth pair 40.

[0018] Each of the support arm pairs 32 pivot on a same support arm pin42 disposed within the assembly frame 18 proximate the caster 22. Thus,the first, second, third, and fourth support arm pairs 34, 36, 38, 40include an identical pivot axis 43 on the assembly frame 18.

[0019] Each of the support arm pairs 32 pivot independently of the othersupport arm pairs 32. For example, the first support arm pair 34 pivotsindependently of the second, third and fourth support arm pairs 36, 38,40. Further, the second support arm pair 36 pivots independently of thefirst, third, and fourth support arm pairs 34, 38, 40. This conceptprovides for the even distribution of rock breaking forces between thecutters 14.

[0020] Each of the cylinders 16 are in fluid communication with ahydraulic circuit 44. The hydraulic circuit 44 provides pressurizedfluid to each cylinder 16 for distributing the downward force to thecutters 14. A fluid accumulator 46 is affixed to the assembly frame 18as shown in FIGS. 1 and 3 for supplying continuous pressure to each ofthe cylinders 16. In the preferred embodiment, the hydraulic pressure isproduced from a fluid pump (not shown) utilized by the machine 12 foralso providing fluid pressure to the machine 12 components. However, afluid pump designated to the cylinders 16 only may also be used.

[0021] Because each of the cutters 14 is affixed to a separate cylinder16, the rock breaking forces can be evenly distributed between thecutters 14. This is most important when breaking rocks embedded in adisparate surface as would be expected when cutting undisturbed rockbeds, such as along a river bank. By evenly distributing the forcesbetween several cutters 14, the lives of the individual cutters 14 areextended. Further, stresses transferred through the assembly 10 are moreevenly distributed, reducing the potential for failures resulting fromstress fractures in the assembly 10.

[0022] The cutters 14 are arranged in a sequential pattern orientedlongitudinally with respect to the machine 12. Thus, the first cutter 14will contact a rock initially, followed sequentially by the second,third and fourth cutters 14. Each of the cutter wheels 24 is arranged inan offset spatial relationship which allows altering the spacing betweenthe path of each cutter 14. Therefore, although the cutters 14 arearranged in a sequential pattern, the overall width of the cutter pathcan be modified by the varying the spacing and number of cutters 14included with the assembly 10.

[0023] Of course, various modifications of this invention would comewithin the scope of the invention. Although the illustrated embodimentincludes an assembly 10 having a single cylinder 16 supporting each ofthe plurality of cutters 14, the invention includes within its scopepairing or otherwise grouping multiple cutters on each of a plurality ofcylinders. Much of the benefit of the disclosed embodiment can still berealized by providing a force distribution mechanism according to thepresent invention which prevents the entire downward force from beingtransmitted through a single cutting wheel.

[0024] Additionally, the use of a caster 22 for pivotally attaching theassembly 10 to a machine 12 reduces side forces on the cutters 14 knownto produce premature failure of the cutter wheels 24.

INDUSTRIAL APPLICABILITY

[0025] The rock breaking assembly of the present invention providessignificant benefits to heavy duty excavation equipment utilizedspecifically for cracking rock and other hard surfaces, such as concreteor asphalt. The improvements over the prior art, which were discussedabove, extend the working life of the rock breaking equipment by evenlydistributing the forces associated with breaking rock over several rockcutting wheels. Other aspects, objects and advantages of this inventioncan be obtained from a study of the drawings, the disclosure and theappended claims.

1. A rock cutting assembly of the type mounted to a machine capable ofexerting downward force, said assembly comprising: a plurality ofcutters; a plurality of cylinders, each of said cylinders supporting atleast one of said cutters; wherein each of said cylinders comprise ahydraulic cylinder for distributing the downward force exerted from themachine.
 2. The assembly of claim 1, further including: an assemblyframe pivotally supporting each of said cylinders; and a casterpivotally affixing said assembly frame to the machine for allowing saidassembly to pivot in a substantially horizontal plane.
 3. An assembly asset forth in claim 2 wherein said assembly frame includes a plurality ofpins affixed thereto for pivotally attaching said cylinders to saidframe and allowing the cylinder to pivot in a substantially verticalplane.
 4. An assembly as set forth in claim 1, wherein each of saidcutters includes a cutter wheel.
 5. An assembly as set forth in claim 6,wherein each of said cutters includes a cutter frame for pivotallysupporting said cutter wheel.
 6. An assembly as set forth in claim 5,wherein said assembly includes a plurality of support arm pairs, each ofsaid support arm pairs having one of said cutter frames fixedly attachedtherebetween.
 7. An assembly as set forth in claim 6, wherein each ofsaid support arm pairs is pivotally attached to said assembly frame atan opposite end thereof from said cutter frames.
 8. An assembly as setforth in claim 6, wherein said plurality of support arm pairs include atleast first pair and a second pair, said first pair disposed betweensaid second pair.
 9. An assembly as set forth in claim 8, wherein saidfirst support arm pair and said second support arm pair include anidentical pivot axis.
 10. An assembly as set forth in claim 9, whereinsaid first support arm pair pivots independently of said second supportarm pair.
 11. An assembly as set forth in claim 1, wherein each of saidcylinders is in communication with a hydraulic fluid circuit, saidhydraulic fluid circuit supplying hydraulic pressure evenly to each saidcylinder.
 12. An assembly as set forth in claim 1, wherein saidplurality of cutters is arranged in a sequential pattern orientedlongitudinally with the machine cutting path.
 13. An assembly as setforth in claim 12, wherein each of said cutter wheels is arranged in anoffset spatial relationship for altering the distance between the cutterpaths.
 14. An assembly as set forth in claim 1, wherein said assemblyincludes a single cylinder independently supporting each of saidplurality of cutters.
 15. A rock cutting assembly comprising: aplurality of cutters; a plurality of cylinders, each supporting at leastone of said cutters; an assembly frame supporting said cylinders; andsaid cylinders being in communication with a hydraulic circuit forproviding downward force to said cutters.
 16. An assembly as set forthin claim 15, further including: a caster pivotally supporting saidassembly frame allowing said assembly frame to pivot in a substantiallyhorizontal plane.
 17. An assembly as set forth in claim 15, wherein saidat least one cutter includes a cutter wheel.
 18. An assembly as setforth in claim 16, wherein said assembly includes at least one supportarm pair, said at least one support arm pair having at least one of saidcutters fixedly attached therebetween.
 19. An assembly as set forth inclaim 18, wherein said at least one support arm pair is pivotallyattached to said assembly frame.
 20. An assembly as set forth in claim19, wherein said at least one support arm pair is disposed between asecond support arm pair.
 21. An assembly as set forth in claim 20,wherein said first support arm pair and said second support arm pairinclude a common pivot axis.
 22. An assembly as set forth in claim 15,wherein said cutters are arranged in an offset spatial relationshipalong a longitudinal cutting path.